Download - Lawrence Thesis (Master)
![Page 1: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/1.jpg)
1
Introduction to Azo Dye Treatment
Aerobic Granular Sludge - A Possible Alternative
Project Objectives and Goals
Methods
Results & Discussion
Summary and Future Work
Outline
HKUST BIOENGINEERING GRADUATE PROGRAM
Sludge Granulation for
Azo Dye Wastewater Treatment
Lawrence, Yan KaiqiSupervisor : Prof. Ka Ming Ng
![Page 2: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/2.jpg)
2
Introduction to Azo Dye Treatment
![Page 3: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/3.jpg)
3
INTRODUCTION TO AZO DYE TREATMENT – Azo Dyes’ Structures
Mordant Orange 1
Coloring Azo Bond
Azo Dyes
Simple synthesis
Good technical performance
Wide color spectrum
70 % of synthetic colorants used in the
textile industry
![Page 4: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/4.jpg)
4
INTRODUCTION TO AZO DYE TREATMENT – Azo Dye Pollution
Dyeing Process
Wat
er
Unc
olor
ed P
rodu
cts
Colored Products
Azo Dyes Wastewater containing 2-50% of original azo dyes
Deeply Colored
Potentially Carcinogenic
and Mutagenic
![Page 5: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/5.jpg)
5
INTRODUCTION TO AZO DYE TREATMENT – Azo Dyes Wastewater Treatment
Azo
Dye
Was
tewa
ter
Trea
tmen
ts
Physicochemical Methods
Ozonation
Photochemical Treatments
Sonolysis
Fenton’s Reagent Oxidation
Adsorption
Chemical Coagulation/ Flocculation with Sedimentation
Biological Methods
Biosorption
Biodegradation
Advanced Oxidation Process
Economical and Environmentally Friendly Option
Require Expensive Equipment and Chemicals
Generate Secondary Waste
![Page 6: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/6.jpg)
6
CO2, H2O, N2 …
Colorless,Harmless
Aerobic Amine Mineralization
INTRODUCTION TO AZO DYE TREATMENT – Conventional Activated Sludge System
Conventional Activated Sludge System
AnaerobicTank
Sedimentation Tank
Sludge SedimentationColor Removal Aromatic Amine Removal
AerobicTank
N
N
R1
R2
NH2 R2
R1 NH2
Azo Dye Aromatic Amines
Colored Colorless, Toxic
Chromophore
Anaerobic Decolorization
![Page 7: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/7.jpg)
7
Aerobic Granular Sludge – A Possible Alternative
![Page 8: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/8.jpg)
8
Aerobic Sludge Granulation:A process of microbial self-
aggregation, by means of biological, physical and chemical phenomena, to help the community achieving better survivability
Microbial cell organized into dense and fast settling pellets with diameter 0.2 mm to around 5 mm
AEROBIC GRANULAR SLUDGE – Introduction to Sludge Granulation
![Page 9: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/9.jpg)
9
AEROBIC GRANULAR SLUDGE – Formation Mechanisms
Aerobic sludge granulation usually occurs in sequencing batch reactors with air aerated at a high superficial velocity
![Page 10: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/10.jpg)
10
AEROBIC GRANULAR SLUDGE – Granulation Process
Hydraulic Shearing
Forces
Flagella Movements
Gravitational Forces
Extracellular Polymeric Substances (EPS)
Chemical Forces Formation of ionic pairs or triplets
with divalent/ trivalent ions
Physical Forces van der Waals Forces, opposite
charge attraction
Biochemical Forces Surface Dehydration,
Membrane Fusion
Step 1Initiation of bacterium-
bacterium contact by physical movements
Step 2Maintaining stable bacterium-
bacterium contact with the establishment of attractive
forces
Step 3Maturation of aerobic granule structures by microbial forces
Step 4Formation of stable 3-
dimensional structure with granules shaped by
hydrodynamic shearing forces
![Page 11: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/11.jpg)
11
AEROBIC GRANULAR SLUDGE – Replication Mechanisms
Sludge growth and aggregation
Shearing forces acting on the
granules cause fragmentation
Internal decay of biomass
resulting in voids and cavities
Reformation of stable granule
structure
![Page 12: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/12.jpg)
12
AEROBIC GRANULAR SLUDGE – Anaerobic Zones in Aerobic Granules
Dead CellsPolysaccharides,
Lipids,
Proteins
Aerobic Zone
Anaerobic Zone
Living AnaerobicBacteria
Living AerobicBacteria
Modified from: Y. Li, Y. Liu, L. Shen and F. Chen, "DO diffusion profile in aerobic granule and its microbiological implications," Enzyme and Microbial Technology, pp. 349-354, 2008.
![Page 13: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/13.jpg)
13
AEROBIC GRANULAR SLUDGE – Comparing to Conventional Activated Sludge
Conventional ActivatedSludge
Granular Sludge
Well – Established Faster Settling Velocity
Higher Biomass Retention
Less Space Consuming
Lower Construction and Operating Costs
Possible to perform simultaneous AN/A reactions
![Page 14: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/14.jpg)
14
AEROBIC GRANULAR SLUDGE – Proposed Azo Dye Degradation Mechansim
Living CellsLiving
AnaerobicBacteria
Living AerobicBacteria
Dead CellsPolysaccharides,
Lipids,
Proteins
MassTransfer
Dye
AnaerobicDecolorization
AromaticAmine Aerobic
Aromatic Amines
Mineralization
HarmlessEnd Products
Fast Settling Velocity
![Page 15: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/15.jpg)
15
Project Objectives and Goals
![Page 16: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/16.jpg)
16
PROJECT OBJECTIVES & GOALS
• To devise a method towards successful cultivation of aerobic granules for azo dye wastewater treatment;
• To demonstrate the developed granules capabilities in performing simultaneous anaerobic decolorization and aerobic aromatic amines mineralization;
• To investigate the effects of different operating parameters to the process performances, including:
• 1. Sludge granular size • 2. Saturated bulk dissolved oxygen
concentration (DO)• 3. Biomass concentration• 4. Organics loading concentration
![Page 17: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/17.jpg)
17
Methods
![Page 18: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/18.jpg)
18
METHODS – Schematic Diagram of the Experiment
Granules Characterization
Morphology and Size Particle Density
Volatile Solid/Solid
Dry Mass/Wet Mass
Sludge Granular Size
Biomass Loading
Bulk Dissolved Oxygen
Organic Loading
Color
Aromatic Amine
COD
Cultivation and Acclimation of
aerobic granules
Performance Tests
![Page 19: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/19.jpg)
19
METHODS – Conventional Granulation of Aerobic Sludge
![Page 20: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/20.jpg)
20
METHODS – Revised Method of Acclimation and Sludge Granulation
![Page 21: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/21.jpg)
21
METHODS – Photo of Aerobic Granules Cultivated in the Project
![Page 22: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/22.jpg)
22
METHODS – Granular Size Control
![Page 23: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/23.jpg)
23
METHODS – Dissolved Oxygen Control
![Page 24: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/24.jpg)
24
METHODS – Verification of the Dissolved Oxygen Control
To verify the method of dissolved oxygen control Mixed gases with different
compressed air to nitrogen ratios were used to maintain a certain oxygen content (%) in it.
The dissolved oxygen concentration of the reactor content was measured by a ODO probe (YSI ProODO™)
For the verifying the method, dissolved oxygen concentrations of different oxygen contents in the mixed gases were also predicted using the Henry’s Law.
![Page 25: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/25.jpg)
25
METHODS – Color Removal Monitoring by UV-Vis Spectrometry
To measure the color intensityThe absorbance at 371.5nm, which is the characteristic peak of the model pollutant Mordant Orange 1, was measured using a UV-Vis spectrophotometer
![Page 26: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/26.jpg)
26
METHODS – Aromatic Amines Monitoring by Diazonium Coupling Reaction
To measure the aromatic amines concentration• Diazonium coupling reaction was
employed to measure the colorless aromatic amines concentration generated during the anaerobic decolorization. The reaction couples the colorless primary aromatic amines with coupling agent and form purplish-pink products, which was then measured using a UV-Vis Spectrometer.
• With different aromatic amines, the reaction is known to produced products with slightly different intensities at different wavelengths of maximum absorbance.
![Page 27: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/27.jpg)
27
METHODS – Diazonium Coupling Reaction Modification
To make accurate measurement of aromatic amines concentration:The theoretical reduction products of mordant orange 1, 4- Nitroaniline (4-NA) and 5- Aminosalicylic acid (5 –ASA), were used to produce a calibration curve for amines monitoring.
![Page 28: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/28.jpg)
28
Results and Discussions -Size, Morphology and Physical Properties of
Aerobic Granules
![Page 29: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/29.jpg)
29
RESULTS & DISCUSSSIONS – Size and Morphology
Diameter and shape descriptors of different sizes granules.
Size Category (a) 0.3 – 1.0 mm
(b) 1.0 – 1.7 mm
(c) 1.7 – 2.4 mm
(d) > 2.4 mm
Area-averaged Diameter (mm) 0.730.22 1.51 0.33 2.420.46 4.120.93
Aspect Ratio 1.690.48 1.490.38 1.380.27 1.300.20
Roundness 0.630.15 0.700.14 0.750.12 0.790.10
Size and morphology of granules• Granules developed in this study had
area-averaged diameters of 0.3 – 5 mm
• The decreasing aspect ratios and increasing roundness with increases in granular size indicate larger granules were more spherical in shape.
![Page 30: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/30.jpg)
30
RESULTS & DISCUSSSIONS – Physical Properties
Physical properties of the cultivated aerobic granules• By Stokes Law, V and d2
• Where V= settling velocity of a spherical particle;
• and d = the particle density and particle diameter;
• The particle density of aerobic granules (1.01 to 1.04 g/cm3) is similar to the density of activated sludge ((1.01-1.06 g/cm3)
• The improved settling velocity is due to the increase in particle diameter instead of the improvement of particle density
![Page 31: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/31.jpg)
31
Results and Discussions -Effect of Sludge Granular Size and Bulk
Dissolved Oxygen Concentration
![Page 32: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/32.jpg)
32
RESULTS & DISCUSSSIONS – COD Removal
% of COD removal of different size granules under different DO• DO , % of COD removal
• Activation of oxygen dependent metabolic pathway that is more energetically efficient.
• Granular size , No significant impact to the % of COD removal in 48 hours, but with COD removal rate.
• Smaller mass transfer resistance in smaller granules
COD removal kinetics of different sizes granules under a dissolved oxygen of 1 ppm
![Page 33: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/33.jpg)
33
RESULTS & DISCUSSSIONS – General Trends of Dye Removal Kinetics
General Trends of Dye Removal Kinetics
Where D = dye content of the commercial dye• Dye equiv. is a collective
measurement of the total amount of dye related compound in the wastewater
• Sudden drop of dye and dye equiv. conc. (120 to 100 ppm) immediately after aerobic granules added
• Initial rapid biosorption• Continuous decolorization with
aromatic amines generation • Reductive decolorization
• Aromatic amines concentration built up faster at the beginning, but dropped later in the experiment
• Simultaneous production and consumption of aromatic amines
Dye remediation kinetics using different sizes granules under different dissolved oxygen levels (▲ represents the Dye Equiv. concentration; represents the color; represents the aromatic amines concentration)
Dye removal kinetics of granules in the size of 1.7 – 2.4 mm under a DO conc of 1 ppm
Sudden drop
![Page 34: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/34.jpg)
34
RESULTS & DISCUSSSIONS – Color Removal
% of Color removal of different size granules under different DO• DO, % of color removal
• Reductive decolorization is favored by the –ve redox potential provided by anaerobic condition
• Oxygen is better e- acceptor
than azo bond• Granular size , % of color removal
• Better synergy in more mature, larger granules
• Granular size , % of color removal is less sensitive to the change in DO concentration
• Smaller change in the anaerobic region to aerobic region ratio
![Page 35: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/35.jpg)
35
RESULTS & DISCUSSSIONS – Color Removal (cont.)
Anaerobic zone in aerobic granules• The thickness of aerobic layer on
aerobic granules is independent to the sludge granular size (Li et. al. (2008))
• Larger granules have larger portions of anaerobic zone in a high DO conc.;
• With the change of the bulk DO conc., smaller granules may change from completely anaerobic to completely aerobic, while larger granules might only change to partially aerobic
• Larger granules have a more stable ratio of anaerobic zone to aerobic zone
![Page 36: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/36.jpg)
36
RESULTS & DISCUSSSIONS – Aromatic Amine Removal
% of Aromatic amines removal of different size granules under different DO• Granular size , % of aromatic amines
removal is less sensitive to the change in DO concentration
• Smaller change in the anaerobic region to aerobic region ratio
• DO , % of aromatic amines removal • Oxygen is required for the
destruction of aromatic structures by the enzymes hydroxylase and oxygenase;
• In low DO, larger granules showed better aromatic amines removal;
• Better synergy in the bacterial community;
• In high DO, smaller granules showed better aromatic amines removal;
• Smaller granules have larger portion of aerobic region in high DO
![Page 37: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/37.jpg)
37
RESULTS & DISCUSSSIONS – Equivalent Dye Removal
% of Equivalent dye removal of different size granules under different DO• DO , Decolorization rate and
aromatic amines mineralization rate ;
• In low DO, the dye removal is limited by the aromatic amines mineralization; In high DO, the dye removal is limited by the decolorization;
• To achieve an optimized dye removal, the decolorization rate and aromatic amines mineralization rate have to be balanced.
![Page 38: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/38.jpg)
38
Results and Discussions -Effect of Biomass Concentration and
Organics Loading Concentration
![Page 39: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/39.jpg)
39
RESULTS & DISCUSSSIONS – Effect of Biomass Concentration
Effect of biomass concentration• Biomass conc. , process
performances ;• From 1.25 g/L to 5 g/L, significant
improvements was observed in all parameters
• More degradation enzymes can be produced with higher biomass concentration.
• Similar % of pollutant removal after 5g/L
• The process may be limited by other factors, including the trace element concentration in the wastewater
![Page 40: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/40.jpg)
40
RESULTS & DISCUSSSIONS – Equivalent Dye Removal
Effect of organic loading concentration• Organic loading played two roles on
the bacterial dye removal, which are:
• (a) Carbon, nitrogen and energy source;
• (b) Electron donors for the reductive decolorization.
• Organic loading conc. , % of color removal , % of aromatic amines removal ;
• More e- generated for reductive decolorization;
• Preferential utilization of organic loadings with simpler structures, instead of aromatic amines
• The optimized organic loading concentration was determined to be 4000 ppm, as which balance the organic loading effect on color and aromatic amines removal.
![Page 41: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/41.jpg)
41
Conclusions and Future Work
![Page 42: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/42.jpg)
42
Conclusions
1. An integrated acclimation and granulation scheme was devised to cultivate aerobic granules for simultaneous anaerobic decolorization/ aerobic aromatic amines mineralization with its performances optimized by varying sludge granular size, bulk dissolved oxygen concentration, biomass concentration and organics loading concentration.
2. A good equivalent dye mineralization (61 2%), decolorization (88 1%), aromatic amines removal (70 3%) and COD removal (88 2%)within 48 hours reaction was obtained by using 5 g/L, 1.0 mm – 1.7 mm granules under a bulk dissolved oxygen concentration of 1 ppm, supplemented with 4000 ppm organic loadings from nutrients.
![Page 43: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/43.jpg)
43
Future Work
1. Although many factors may affect the size of granules cultivated in the reactor, no technique is currently available to control granular size. The design of sludge granular size controlling method may be important towards a better performances of aerobic sludge granulation system using in azo dye wastewater treatment.
2. Only a single model pollutant, Mordant Orange 1, was used in this study. In real life textile wastewater, other constituents, including surfactants, may exist and damage the developed granulation system. A further investigation of using the developed system for treating real textile wastewater may also be necessary.
3. The techniques of sludge granulation may not only applicable in wastewater treatment, but also in mass production of other bacterial metabolite. The faster settling velocity, higher biomass concentration and easier separation of the biomass from the liquid content may lead to the development of production process with more efficient conversion and easier downstream processes.
![Page 44: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/44.jpg)
44
Acknowledgements
![Page 45: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/45.jpg)
45
Acknowledgement
SupervisorProf. Ka Ming NG
Thesis examination committee Prof. Guohua CHEN and Prof. Henry LAM
Thesis supervision committeeProf. Xi Jun HU and Prof. David HUI
Wastewater treatment teamDr. Kelvin FUNG, Dr. Judy Zhang, Ms. Pinky Sin
Technical Staff in CBMEMr. Hoi Yau CHENG, Mr. Wing Li LEUNG, Mr. Kam Tim TANG
Technical and administrative Staff in BIENMs. Inez TSUI, Ms Zoei CHU, Ms Winnie LEUNG
Labmates and FriendsMy family members
![Page 46: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/46.jpg)
46
Thank You
![Page 47: Lawrence Thesis (Master)](https://reader035.vdocuments.us/reader035/viewer/2022062522/58855fa71a28ab47268b7085/html5/thumbnails/47.jpg)
47
METHODS – Selective Pressure Theory
By Stokes Law:The free settling velocity of a spherical sediment is given by:
Where V = the settling velocity of the sediment= the allowed Settling Time L = the liquid level above the disposal porti.e. Volumetric Exchange Ratio Dp = the diameter of the sediment particle the density of the sediment = the density of the settling medium the viscosity of the settling Medium
• Settling time and volumetric exchange ratio were known to be influential to the granule formation and thus be regarded as the selective pressures of the aerobic sludge granulation,
• As short settling time and high volume exchange ratio will result in a larger wash out of reactor content, such conditions were also known as with high selective pressures